When treating tissue such as tumors in the brain, the prostate, the trunk of the body, the liver, the chest, etc., a solid, liquid or gaseous substance, such as a radioactive substance, for example, can be delivered into the tissue or into the vicinity of the tissue, to perform so-called near-field irradiation on the infected tissue. The introduced radioactive solids, liquids or gases which, for example, emit beta radiation, can destroy the tumor.
As an alternative to these brachytherapy methods wherein tissue is irradiated using a radioactive substance introduced into or in the vicinity of the tissue to be irradiated, a radiotherapeutic or radiosurgical method also can be performed. In radiotherapeutic or radiosurgical methods, for example, the tissue can be irradiated using a radiation source guided or positioned around the body. In this case, substances (so-called sensitizers) are often introduced into the body, in particular into the area of the tissue to be treated. The substances, for example, can make tumor cells more sensitive to radioactive or light beams or also to the effect of heat. In treating a tumor, high doses of said sensitizers and high radiation doses generally are used in order to kill the bulk of the tumor cells. However, administering a high dose of sensitizers or irradiating body tissue with a high dose of radioactive radiation can also have undesirable effects on healthy tissue that is not to be treated.
Infusing medicines into the brain to treat neurodegenerative dysfunctions by means of an implantable pump and a catheter is known from U.S. Pat. No. 5,735,814, wherein the stimulus levels of the neurons in the brain are altered by means of the administered substances.
U.S. Pat. No. 6,026,316 describes monitoring the administration of a substance by means of nuclear spin tomography.
A solid substance which can be used in brachytherapy and which can be implanted is known from U.S. Pat. No. 6,746,661 B2.